Introduction Intravaginal rings are used worldwide, mostly for contraception, and are now being investigated for pre-exposure prophylaxis for HIV and multipurpose technologies that combine antiviral products with contraception. Despite its ubiquitous use, little research has been done to study the effect of the vaginal microbiome on these rings.
Methods The amount of bacterial biofilm was assessed using crystal violet staining (CV) on 403 contraceptive intravaginal rings (CVR) worn for 21 days by 120 women participating in a CVR clinical trial in Rwanda. A subset of 22 CVRs was evaluated by confocal microscopy after Fluorescence In Situ Hybridization (FISH) with species-specific probes for A. vaginae (Av), G. vaginalis (Gv) and for theLactobacillus genus (Lsp). At each CVR-removal visit, vaginal slides were made for Nugent scoring to diagnose bacterial vaginosis (BV) and FISH to assess the presence of Av and Gv biofilm.
Results A higher amount of biofilm on the CVR, according to CV, was associated with the presence of vaginal biofilm of Av (p < 0.001) and Gv (p = 0.002), but less with vaginal planktonic Av (p = 0.026) and not with dispersed Gv (p = 0.189), visualised with FISH. A higher amount of CVR-biofilm was also found in participants suffering from BV compared to women with a healthy vaginal microbiome (p < 0.001). FISH of the CVRs showed large areas of the ring surfaces covered with biofilm of vaginal epithelial cells and bacteria. BV-associated bacteria were included in the biofilm, as well as health-associated lactobacilli.
Conclusion Our study shows that biofilm is common on IVRs and consists of vaginal cells and microbes residing in the vagina: BV-associated bacteria and lactobacilli. The presence of biofilm of BV-associated bacteria in the vagina however leads to an increase of biofilm on the IVRs and might contribute to the persistence of the condition or could hamper the release of active product.
This work was supported by European and Developing Countries Clinical Trials Partnerships (EDCTP), by Combined Highly Active Anti-Retroviral Microbicides (CHAARM) and by Dormeur Investment Service. No pharmaceutical grants were received in the development of this study.